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feedback on cabinet design for 2235
hi,
I am trying to design some new cabinets for my 2235 drivers. I know the JBL enclosure guide gives measurements, but I would like non-parallel walls and I like my horn at ear height. The standard JBL recommended size does not allow that.
Measurements here are in cm., this gives a volume of about 150 liters [which is about qubic 5ft for those who do not know wat a "cheese royale" is]
Does anyone have any thoughts on this design? Positive or negative?
edit>> WOW, I now see this was POST NR 100! finally I am getting somewhere!
Regards, Frank
250Ti Woofer Height? Only Speculation, but;
John W
Quote:
Originally Posted by John W
Also, I was looking at the sales brochure for the 250Ti and it has the line “Low frequency driver is precise height from floor to give best balanced bass response”. I have not heard much about this, but what is that best height?
- LF & MF cancellation ( caused by a wave reflecting off of a very hard surface ) is a real and significant factor effecting the smooth playback of certain frequency areas. A "bounced wave" can quite easily propagate a new wave that is 180° out of phase to the original . Add the out of phase wave to the original and you get cancellation of various degrees .
- These cancellations aren't as narrowband as I may have implied. I've measured them to sometimes be almost a 2/3 of octave wide ( the width of the null will be effected by the diameter of the woofer under study ). The shape of the attenuation can be remarkably uniform resembling a "V" / cut into an otherwise straightline response .
- Maybe the designer found a reason to use the floor to moderate or attenuate a response bump found in the 300 hz area. Why the bump ? Maybe the answer is single driver related ( le14h-1 ) or maybe it's a function of two drivers plus the chosen crossover slopes , I really don't know the particulars.
- An example ; 1130 ( the speed of sound used by many ) divided by 300 hz = 3.767 ft ( or 45.2" ). This is the wavelength in inches . Divide that by 2 to arrive at 22.6" ( for 1/2 wave bounce-cancellation to occur centered around 300 hz )
- Look at a scaled 250ti picture / note the apparent distance from the bottom up to the center of the 14" speaker. Roughly, to my eyes, the distance appears to be about a woofer & a half / or 21" ( roughly corresponding to 325 hz ) .
- Conjecture on my part that can't go much further without building a 250ti in an anechoic environment ( & that's not going to happen ) .
:)